The invention relates to a process for polishing silicon wafers. More particularly, the invention relates to a process for polishing silicon wafers wherein a protective film is produced on the wafer surface thereby assuring the quality of the wafer surface.
A number of methods of polishing silicon wafers have become known, including, for example, the process according to German Pat. DE-OS No. 23 05 188 or U.S. Pat. No. 4,070,797.
The common feature of the known methods is that the polished wafers are exposed to many influences during the period between the actual polishing step and the final drying and packaging. These influences or effects include, for example, uncontrolled chemical reactions caused by residual amounts of the generally alkaline polishing agent still adhering to the wafers, and by cleaning solutions or water. These effects may cause a deterioration of the quality of the surface which is noticed as a so-called "haze" when the surface is inspected under a sharply focused intense light beam, i.e., as a milky-grey area at the point of incidence. The milky-gray areas are caused by the scattering of the light in slightly roughened sections of the area. In the manufacture of electronic components, however, it is of the utmost importance to have silicon wafers which are haze-free, primarily in view of the fact that increasingly exacting surface quality requirements have to be satisfied. These requirements relate primarily to the constantly progressing miniaturization of electronic components and the need to have silicon wafers which do not have these effects on surface quality that are detachable or observable as a haze.
Accordingly, it is an object of the invention to provide a method of polishing silicon wafers which assures that the quality of the surface of the polished wafers is not influenced by the processing or finishing steps which follow the polishing step.